裂隙岩体中隧道开挖流固耦合模型及开挖诱发损伤分析

Hydro-mechanical coupling model for tunnel excavation in fractured rocks and analysis on excavation-induced damage

裂隙岩体中隧道开挖会诱发强烈的流固耦合效应,从而引发显著的岩体损伤和水压力扰动,针对该问题,首先建立了一种计算裂隙岩体中隧道开挖和后续排水诱发损伤和裂隙变形的流固耦合模型,然后对不同参数化裂隙网络进行了模拟,最后针对模拟结果给出了实例分析。研究结果表明:所建模型可有效模拟含裂隙网络的岩体中隧道开挖和后续排水降压过程以及岩体损伤发展、裂隙变形和地下水渗流过程;岩体裂隙网络显著影响应力分布的均匀性,隧道开挖和地下水渗流的耦合作用造成隧道周围极易出现高应力区,且局部应力、裂隙变形和水压力之间呈现出显著相关性;不同裂隙网络的分布特征在隧道开挖诱发损伤发展中起到主导作用,进而影响隧道开挖扰动区和损伤区的形成与发展程度。

Tunnel excavation in fractured rock masses will induce a strongly hydro-mechanical coupling effect,which may cause significant rock mass damage and water pressure perturbation.This paper establishes a hydro-mechanical model to analyze the rock damage and fracture deformation induced by the tunnel excavation and the sequential drainage phase in fractured rocks.Afterwards,the model is used to investigate the effect of fracture networks on the excavation-induced damage in different fracture networks.It was found that the proposed model can effectively simulate the tunnel excavation and drainage phases in rocks embedded with discrete fracture networks.The damage evolution,fracture deformation,and groundwater seepage were well-captured in the simulation.The fracture network was found to significantly affect the uniformity of stress distribution.The coupling effect of tunnel excavation and groundwater seepage caused high stress zones around the tunnel,and there was a significant correlation between local stress,fracture deformation and water pressure.The distribution characteristics of fracture networks played a leading role on the development of excavation-induced damage,which further influenced the formation and development of excavation disturbed zone and excavation damaged zone.